Stream-splitter devices are used to divide a primary flow into a plurality of satellite flows which are supplied to a number of processing devices. Often one of the satellite flows is used to periodically extract samples of the flow for testing and evaluating. Typically the primary reservoir or tank is vertically oriented and satellite flows emerge from identical orifices at the same level to ensure equality among the satellite flows. Each of the satellite flows is directed into a satellite conduit in which the level is beneath the level of the orifice in order that each orifice work into the same pressure, e.g. atmospheric, regardless of any difference in downstream loading, impedance or back pressure. While this approach serves to produce equal flow in each satellite conduit regardless of downstream flow differences, it introduces another problem: it allows air to be entrapped in the flow in the satellite conduit. The entrapped air can cause problems in controlling the pressure and flow in the processing satellite devices and can cause cavitation, turbulence and otherwise interfere with subsequent processing. Recently it has been suggested to use a feedback system employing a number of parts, electrical, mechanical or hydraulic, including a level sensor, pressure sensor or other condition monitor associated with the flow in a satellite conduit to operate a valve associated with the same satellite conduit to maintain the pressure in that satellite conduit at a predetermined level above ambient.